/*** includes ***/

#define _DEFAULT_SOURCE
#define _BSD_SOURCE
#define _GNU_SOURCE

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <stdarg.h>
#include <fcntl.h>

/*** defines ***/

#define KILO_VERSION "0.0.1"
#define KILO_TAB_STOP 8
#define KILO_QUIT_TIMES 3

#define CTRL_KEY(k) ((k) & 0x1f)

enum editorKey {
	BACKSPACE = 127,
	ARROW_LEFT = 1000,
	ARROW_RIGHT,
	ARROW_UP,
	ARROW_DOWN,
	DEL_KEY,
	HOME_KEY,
	END_KEY,
	PAGE_UP,
	PAGE_DOWN
};

enum editorHighligh {
	HL_NORMAL = 0,
	HL_COMMENT,
	HL_MLCOMMENT,
	HL_KEYWORD1,
	HL_KEYWORD2,
	HL_STRING,
	HL_NUMBER,
	HL_MATCH
};

#define HL_HIGHLIGHT_NUMBERS (1<<0)
#define HL_HIGHLIGHT_STRINGS (1<<1)
/*** data ***/

struct editorSyntax {
	char* filetype;
	char** filematch;
	char** keywords;
	char* singleline_comment_start;
	char* multiline_comment_start;
	char* multiline_comment_end;
	int flags;
};

typedef struct erow {
	int idx;
	int size;
	int rsize;
	char* render;
	char* chars;
	unsigned char* hl;
	int hl_open_comment;
} erow;

struct editorConfig {
	int cx, cy;
	int rx;
	int rowoff;
	int coloff;
	int screenrows;
	int screencols;
	int numrows;
	erow* row;
	int dirty;
	char* filename;
	char statusmsg[80];
	time_t statusmsg_time;
	struct editorSyntax* syntax;
	struct termios orig_termios;
} E;

/*** filetypes ***/
char* C_HL_extensions[] = {".c", ".h", ".cpp", NULL};
char* C_HL_keywords[] = {
	"switch", "if", "while", "for", "break", "continue", "return", "else",
	"struct", "union", "typedef", "static", "enum", "class", "case",
	
	"int|", "long|", "double|", "float|", "char|", "unsigned|", "signed|",
	"void|", NULL
};
struct editorSyntax HLDB[] = {
	{
		"c",
		C_HL_extensions,
		C_HL_keywords,
		"//", "/*", "*/",
		HL_HIGHLIGHT_NUMBERS | HL_HIGHLIGHT_STRINGS
	},
};

#define HLDB_ENTRIES (sizeof(HLDB) / sizeof(HLDB[0]))

/*** prototypes ***/

void editorSetStatusMessage(const char* fmt, ...);
void editorRefreshScreen();
char* editorPrompt(char* prompt, void (*callback)(char *, int));

/*** terminal ***/

void die(const char* s) {
	write(STDOUT_FILENO, "\x1b[2J", 4);
	write(STDOUT_FILENO, "\x1b[H", 3);

	perror(s);
	exit(1);
}

void disableRawMode() {
	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &E.orig_termios) == -1)
		die("tcsetattr");
}

void enableRawMode() {
		if (tcgetattr(STDIN_FILENO, &E.orig_termios) == -1)
			die("tcgetattr");
		atexit(disableRawMode);
		
		struct termios raw = E.orig_termios;		
		raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
		raw.c_oflag &= ~(OPOST);
		raw.c_cflag |= (CS8);
		raw.c_lflag &= ~(ECHO | ICANON | IEXTEN |ISIG);
		raw.c_cc[VMIN] = 0;
		raw.c_cc[VTIME] = 1;
		
		if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1)
			die("tcsetattr");
}

int editorReadKey() {
	int nread;
	char c;
	while ((nread = read(STDIN_FILENO, &c, 1)) != 1) {
		if (nread == -1 && errno != EAGAIN) die("read");
	}
	
	if (c == '\x1b') {
		char seq[3];
		
		if (read(STDIN_FILENO, &seq[0], 1) != 1) return '\x1b';
		if (read(STDIN_FILENO, &seq[1], 1) != 1) return '\x1b';
		
		if (seq[0] == '[') {
			if (seq[1] >= '0' && seq[1] <= '9') {
				if (read(STDIN_FILENO, &seq[2], 1) != 1) return '\x1b';
				if (seq[2] == '~') {
					switch (seq[1]) {
						case '1': return HOME_KEY;
						case '3': return DEL_KEY;
						case '4': return END_KEY;
						case '5': return PAGE_UP;
						case '6': return PAGE_DOWN;
						case '7': return HOME_KEY;
						case '8': return END_KEY;
					}
				}
			} else {
				switch (seq[1]) {
					case 'A': return ARROW_UP;
					case 'B': return ARROW_DOWN;
					case 'C': return ARROW_RIGHT;
					case 'D': return ARROW_LEFT;
					case 'H': return HOME_KEY;
					case 'F': return END_KEY;
				}
			} 
		} else if (seq[0] == 'O') {
			switch (seq[1]) {
				case 'H': return HOME_KEY;
				case 'F': return END_KEY;
			}
		}
		
		return '\x1b';
	} else {
		return c;
	}
}

int getCursorPosition(int* rows, int* cols) {
	char buf[32];
	unsigned int i = 0;

	if (write(STDOUT_FILENO, "\x1b[6n", 4) != 4) return -1;

	while (i < sizeof(buf) - 1) {
		if (read(STDIN_FILENO, &buf[i], 1) != 1) break;
		if (buf[i] == 'R') break;
		i++;
	}
	buf[i] = '\0';
	
	if (buf[0] != '\x1b' || buf[1] != '[') return -1;
	if (sscanf(&buf[2], "%d;%d", rows, cols) != 2) return -1;
	
	return 0;
}

int getWindowSize(int* rows, int* cols) {
	struct winsize ws;
	
	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0) {
		if (write(STDOUT_FILENO, "\x1b[999C\x1b[999B", 12) != 12) return -1;
		return getCursorPosition(rows, cols);
	}
	*cols = ws.ws_col;
	*rows = ws.ws_row;
	return 0;
}

/*** syntax highlighting ***/

int isSeparator(int c) {
	return isspace(c) || c == '\0' || strchr(",.()+-/*=~%<>[];", c) != NULL;
}

void editorUpdateSyntax(erow* row) {
	row->hl = realloc(row->hl, row->rsize);
	memset(row->hl, HL_NORMAL, row->rsize);
	
	if (E.syntax == NULL) return;
	
	char** keywords = E.syntax->keywords;
	
	char* scs = E.syntax->singleline_comment_start;
	char* mcs = E.syntax->multiline_comment_start;
	char* mce = E.syntax->multiline_comment_end;
	
	int scs_len = scs ? strlen(scs) : 0;
	int mcs_len = mcs ? strlen(mcs) : 0;
	int mce_len = mce ? strlen(mce) : 0;
	
	int prev_sep = 1;
	int in_string = 0;
	int in_comment = (row->idx > 0 && E.row[row->idx - 1].hl_open_comment);
	
	int i = 0;
	while (i < row->rsize) {
		char c = row->render[i];
		unsigned char prev_hl = (i > 0) ? row->hl[i - 1] : HL_NORMAL;
		
		if (scs_len && !in_string  && !in_comment) {
			if (!strncmp(&row->render[i], scs, scs_len)) {
				memset(&row->hl[i], HL_COMMENT, row->rsize - i);
				break;
			}
		}
		
		if (mcs_len && mce_len && !in_string) {
			if (in_comment) {
				row->hl[i] = HL_MLCOMMENT;
				if (!strncmp(&row->render[i], mce, mce_len)) {
					memset(&row->hl[i], HL_MLCOMMENT, mce_len);
					i += mce_len;
					in_comment = 0;
					prev_sep =  1;
					continue;
				} else {
					i++;
					continue;
				}
			} else if (!strncmp(&row->render[i], mcs, mcs_len)) {
				memset(&row->hl[i], HL_MLCOMMENT, mcs_len);
				i += mcs_len;
				in_comment = 1;
				continue;
			}
		}
		
		if (E.syntax->flags & HL_HIGHLIGHT_STRINGS) {
			if (in_string) {
				row->hl[i] = HL_STRING;
				if (c == '\\' && i + 1 < row->rsize) {
					row->hl[i + 1] = HL_STRING;
					i += 2;
					continue;
				}
				if (c == in_string) in_string = 0;
				i++;
				prev_sep = 1;
				continue;
			} else {
				if (c == '"' || c == '\'') {
					in_string = c;
					row->hl[i] = HL_STRING;
					i++;
					continue;
				}
			}
		}
		
		if (E.syntax->flags & HL_HIGHLIGHT_NUMBERS) {
			if ((isdigit(c) && (prev_sep || prev_hl == HL_NUMBER)) ||
				(c == '.' && prev_hl == HL_NUMBER)) {
				row->hl[i] = HL_NUMBER;
				i++;
				prev_sep = 0;
				continue;
			}
		}
		
		if (prev_sep) {
			int j;
			for (j = 0; keywords[j]; j++) {
				int klen = strlen(keywords[j]);
				int kw2 = keywords[j][klen - 1] == '|';
				if (kw2) klen--;
				
				if (!strncmp(&row->render[i], keywords[j], klen) &&
					isSeparator(row->render[i + klen])) {
					memset(&row->hl[i], kw2 ? HL_KEYWORD2 : HL_KEYWORD1, klen);
					i += klen;
					break;
				}
			}
			if (keywords[j] != NULL) {
				prev_sep = 0;
				continue;
			}
		}
		
		prev_sep = isSeparator(c);
		i++;
	}
	
	int changed = (row->hl_open_comment != in_comment);
	row->hl_open_comment = in_comment;
	if (changed && row->idx + 1 < E.numrows) {
		editorUpdateSyntax(&E.row[row->idx + 1]);
	}
}

int editorSyntaxToColor(int hl) {
	switch (hl) {
		case HL_COMMENT:
		case HL_MLCOMMENT: return 36;
		case HL_KEYWORD1: return 33;
		case HL_KEYWORD2: return 32;
		case HL_STRING: return 35;
		case HL_NUMBER: return 31;
		case HL_MATCH: return 34;
		default: return 37;
	}
}

void editorSelectSyntaxHighlight() {
	E.syntax = NULL;
	if (E.filename == NULL) return;
	
	char* ext = strrchr(E.filename, '.');
	
	for (unsigned int j = 0; j < HLDB_ENTRIES; j++) {
		struct editorSyntax* s = &HLDB[j];
		unsigned int i = 0;
		while (s->filematch[i]) {
			int is_ext = (s->filematch[i][0] == '.');
			if ((is_ext && ext && !strcmp(ext, s->filematch[i])) ||
				(!is_ext && strstr(E.filename, s->filematch[i]))) {
				E.syntax = s;
				
				for (int filerow = 0; filerow < E.numrows; filerow++) {
					editorUpdateSyntax(&E.row[filerow]);
				}
				
				return;
			}
			i++;
		}
	}
}

/*** row operations ***/

int editorRowCxToRx(erow* row, int cx) {
	int rx = 0;
	for (int j = 0; j < cx; j++) {
		if (row->chars[j] == '\t')
			rx += (KILO_TAB_STOP - 1) - (rx % KILO_TAB_STOP);
		rx++;
	}
	return rx;
}

int editorRowRxToCx(erow* row, int rx) {
	int cur_rx = 0;
	int cx;
	for (cx = 0; cx < row->size; cx++) {
		if (row->chars[cx] == '\t')
			cur_rx += (KILO_TAB_STOP - 1) - (cur_rx % KILO_TAB_STOP);
		cur_rx++;
		
		if (cur_rx > rx) return cx;
	}
	return cx;
}

void editorUpdateRow(erow* row) {
	int tabs = 0;
	for (int j = 0; j < row->size; j++) {
		if (row->chars[j] == '\t') tabs++; 
	}
	
	free(row->render);
	row->render = malloc(row->size + tabs*(KILO_TAB_STOP - 1) + 1);
	
	int idx = 0;
	for (int j = 0; j < row->size; j++) {
		if (row->chars[j] == '\t') {
			row->render[idx++] = ' ';
			while (idx % KILO_TAB_STOP != 0) row->render[idx++] = ' ';
		} else {
			row->render[idx++] = row->chars[j];
		}
	}
	row->render[idx] = '\0';
	row->rsize = idx;
	
	editorUpdateSyntax(row);
}

void editorInsertRow(int at, char* s, size_t len){
	if (at < 0 || at > E.numrows) return;

	E.row = realloc(E.row, sizeof(erow) * (E.numrows + 1));
	memmove(&E.row[at + 1], &E.row[at], sizeof(erow) * (E.numrows - at));
	for (int j = at + 1; j <= E.numrows; j++) E.row[j].idx++; 
	
	E.row[at].idx = at;
	
	E.row[at].size = len;
	E.row[at].chars = malloc(len + 1);
	memcpy(E.row[at].chars, s, len);
	E.row[at].chars[len] = '\0';
	
	E.row[at].rsize = 0;
	E.row[at].render = NULL;
	E.row[at].hl = NULL;
	E.row[at].hl_open_comment = 0;
	editorUpdateRow(&E.row[at]);
	
	E.numrows++;
	E.dirty++;
}

void editorFreeRow(erow* row) {
	free(row->render);
	free(row->chars);
	free(row->hl);
}

void editorDelRow(int at) {
	if (at < 0 || at >= E.numrows) return;
	editorFreeRow(&E.row[at]);
	memmove(&E.row[at], &E.row[at + 1], sizeof(erow) * (E.numrows - at - 1));
	for (int j = at; j < E.numrows - 1; j++) E.row[j].idx--;
	E.numrows--;
	E.dirty++;
}

void editorRowInsertChar(erow* row, int at, int c) {
	if (at < 0 || at > row->size) at = row->size;
	row->chars = realloc(row->chars, row->size + 2);
	memmove(&row->chars[at + 1], &row->chars[at], row->size - at + 1);
	row->size++;
	row->chars[at] = c;
	editorUpdateRow(row);
	E.dirty++;
}

void editorRowAppendString(erow* row, char* s, size_t len) {
	row->chars = realloc(row->chars, row->size + len + 1);
	memcpy(&row->chars[row->size], s, len);
	row->size += len;
	row->chars[row->size] = '\0';
	editorUpdateRow(row);
	E.dirty++;
}

void editorRowDelChar(erow* row, int at) {
	if (at < 0 || at >= row->size) return;
	memmove(&row->chars[at], &row->chars[at + 1], row->size - at);
	row->size--;
	editorUpdateRow(row);
	E.dirty++;
}

/*** editor operations ***/

void editorInsertChar(int c) {
	if (E.cy == E.numrows) {
		editorInsertRow(E.numrows, "", 0);
	}
	editorRowInsertChar(&E.row[E.cy], E.cx, c);
	E.cx++;
}

void editorInsertNewline() {
	if (E.cx == 0) {
		editorInsertRow(E.cy, "", 0);
	} else {
		erow* row = &E.row[E.cy];
		editorInsertRow(E.cy + 1, &row->chars[E.cx], row->size - E.cx);
		row = &E.row[E.cy];
		row->size = E.cx;
		row->chars[row->size] = '\0';
		editorUpdateRow(row);
	}
	E.cy++;
	E.cx = 0;
}

void editorDelChar() {
	if (E.cy == E.numrows) return;
	if (E.cx == 0 && E.cy == 0) return;
	
	erow* row = &E.row[E.cy];
	if (E.cx > 0) {
		editorRowDelChar(row, E.cx - 1);
		E.cx--;
	} else {
		E.cx = E.row[E.cy - 1].size;
		editorRowAppendString(&E.row[E.cy - 1], row->chars, row->size);
		editorDelRow(E.cy);
		E.cy--;
	}
}

/*** file i/o ***/

char* editorRowsToString(int* buflen) {
	int totlen = 0;
	for (int i = 0; i < E.numrows; i++) {
		totlen += E.row[i].size + 1;
	}
	*buflen = totlen;
	
	char* buf = malloc(totlen);
	char* p = buf;
	for (int i = 0; i < E.numrows; i++) {
		memcpy(p, E.row[i].chars, E.row[i].size);
		p += E.row[i].size;
		*p = '\n';
		p++;
	}
	
	return buf;
}

void editorOpen(char* filename) {
	free(E.filename);
	E.filename = strdup(filename);
	
	editorSelectSyntaxHighlight();
	
	FILE* fp = fopen(filename, "r");
	if (!fp) die("fopen");
	
	char* line = NULL;
	ssize_t lineLen;
	size_t lineCap = 0;	
	while ((lineLen = getline(&line, &lineCap, fp)) != -1) {
		while (lineLen > 0 && (line[lineLen - 1] == '\n' || 
								line[lineLen - 1] == '\r'))
			lineLen--;
		editorInsertRow(E.numrows, line, lineLen);
	}
	free(line);
	fclose(fp);
	E.dirty = 0;
}

void editorSave() {
	if (E.filename == NULL) {
		E.filename = editorPrompt("Save as: %s", NULL);
		if (E.filename == NULL) {
			editorSetStatusMessage("Save aborted");
			return;
		}
		editorSelectSyntaxHighlight();
	}
	
	int len;
	char* buf = editorRowsToString(&len);
	
	int fd = open(E.filename, O_RDWR | O_CREAT, 0644);
	if (fd != -1) {
		if (ftruncate(fd, len) != -1) {
			if (write(fd, buf, len) == len) {
				close(fd);
				free(buf);
				E.dirty = 0;
				editorSetStatusMessage("%d bytes written to disk", len);
				return;
			}
		}
		close(fd);
	}
	
	free(buf);
	editorSetStatusMessage("Can't save! I/O error: %s", strerror(errno));
}

/*** find ***/

void editorFindCallback(char* query, int key) {
	static int last_match = -1;
	static int direction = 1;
	
	static int saved_hl_line;
	static char* saved_hl = NULL;
	
	if (saved_hl) {
		memcpy(E.row[saved_hl_line].hl, saved_hl, E.row[saved_hl_line].rsize);
		free(saved_hl);
		saved_hl = NULL;
	}
	
	if (key == '\r' || key == '\x1b') {
		last_match = -1;
		direction = 1;
		return;
	} else if (key == ARROW_RIGHT || key == ARROW_DOWN) {
		direction = 1;
	} else if (key == ARROW_LEFT || key == ARROW_UP) {
		direction = -1;
	} else {
		last_match = -1;
		direction = 1;
	}
	
	if (last_match == -1) direction = 1;
	int current = last_match;
	for (int i = 0; i < E.numrows; i++) {
		current += direction;
		if (current == -1) current = E.numrows - 1;
		else if (current == E.numrows) current = 0;
		
		erow* row = &E.row[current];
		char* match = strstr(row->render, query);
		if (match) {
			last_match = current;
			E.cy = current;
			E.cx = editorRowRxToCx(row, match - row->render);
			E.rowoff = E.numrows;
			
			saved_hl_line = current;
			saved_hl = malloc(row->rsize);
			memcpy(saved_hl, row->hl, row->rsize);
			memset(&row->hl[match - row->render], HL_MATCH, strlen(query));
			break;
		}
	}
}

void editorFind() {
	int saved_cx = E.cx;
	int saved_cy = E.cy;
	int saved_coloff = E.coloff;
	int saved_rowoff = E.rowoff;

	char* query = editorPrompt("Search: %s (Use ESC/Arrows/Enter)",
								editorFindCallback);
	
	if (query) {
		free(query);
	} else {
		E.cx = saved_cx;
		E.cy = saved_cy;
		E.coloff = saved_coloff;
		E.rowoff = saved_rowoff;
	}
}

/*** append buffer ***/

struct abuf {
	char* b;
	int len;
};

#define ABUF_INIT {NULL, 0}

void abufAppend(struct abuf* ab, const char* s, int len) {
	char* new = realloc(ab->b, ab->len + len);
	
	if (new == NULL) return;
	memcpy(&new[ab->len], s, len);
	ab->b = new;
	ab->len += len;
}

void abufFree(struct abuf* ab) {
		free(ab->b);
}

/*** output ***/

void editorScroll() {
	E.rx = 0;
	if (E.cy < E.numrows) {
		E.rx = editorRowCxToRx(&E.row[E.cy], E.cx);
	}
	
	if (E.cy < E.rowoff) {
		E.rowoff = E.cy;
	}
	if (E.cy >= E.rowoff + E.screenrows) {
		E.rowoff = E.cy - E.screenrows + 1;
	}
	if (E.rx < E.coloff) {
		E.coloff = E.rx;
	}
	if (E.rx >= E.coloff + E.screencols) {
		E.coloff = E.rx - E.screencols + 1;
	}
}

void editorDrawRows(struct abuf* ab) {
	for (int i = 0; i < E.screenrows; i++) {
		int fileRow = i + E.rowoff;
		if (fileRow >= E.numrows) {
			if (E.numrows == 0 && i == E.screenrows / 3) {
				char welcome[80];
				int welcomeLen = snprintf(welcome, sizeof(welcome), 
					"Kilo editor -- version %s", KILO_VERSION);
				if (welcomeLen > E.screencols) welcomeLen = E.screencols;
				int padding = (E.screencols - welcomeLen) / 2;
				if (padding) {
					abufAppend(ab, "~", 1);
					padding--;
				}
				while (padding--) abufAppend(ab, " ", 1);
				abufAppend(ab, welcome, welcomeLen);				
			} else {
				abufAppend(ab, "~", 1);
			}
		} else {
			int len = E.row[fileRow].rsize - E.coloff;
			if (len < 0) len = 0;
			if (len > E.screencols) len = E.screencols;
			char* c = &E.row[fileRow].render[E.coloff];
			unsigned char* hl = &E.row[fileRow].hl[E.coloff];
			int current_color = -1;
			for (int j = 0; j < len; j++) {
				if (iscntrl(c[j])) {
					char sym = (c[j] <= 26) ? '@' + c[j] : '?';
					abufAppend(ab, "\x1b[7m", 4);
					abufAppend(ab, &sym, 1);
					abufAppend(ab, "\x1b[m", 3);
					if (current_color != -1) {
						char buf[16];
						int clen = snprintf(buf, sizeof(buf), "x1b[%dm", current_color);
						abufAppend(ab, buf, clen);
					}
				} else if (hl[j] == HL_NORMAL) {
					if (current_color != -1) {
						abufAppend(ab, "\x1b[39m", 5);
						current_color = -1;
					}
					abufAppend(ab, &c[j], 1);
				} else {
					int color = editorSyntaxToColor(hl[j]);
					if (color != current_color) {
						current_color = color;
						char buf[16];
						int clen = snprintf(buf, sizeof(buf), "\x1b[%dm", color);
						abufAppend(ab, buf, clen);
					}					
					abufAppend(ab, &c[j], 1);
				}
			}
			abufAppend(ab, "\x1b[39m", 5);
		}
		
		abufAppend(ab, "\x1b[K", 3);
		abufAppend(ab, "\r\n", 2);
	}
}

void editorDrawStatusBar(struct abuf* ab) {
	abufAppend(ab, "\x1b[7m", 4);
	char status[80], rstatus[80];
	int len = snprintf(status, sizeof(status), "%.20s - %d lines %s", 
		E.filename ? E.filename : "[No Name]", E.numrows, 
		E.dirty ? "(modified)" : "");
	int rlen = snprintf(rstatus, sizeof(rstatus), "%s %d/%d",
		E.syntax ? E.syntax->filetype : "no ft", E.cy + 1, E.numrows);
	if (len > E.screencols) len = E.screencols;
	abufAppend(ab, status, len);
	while (len < E.screencols) {
		if (E.screencols - len == rlen) {
			abufAppend(ab, rstatus, rlen);
			break;
		} else {
			abufAppend(ab, " ", 1);
			len++;
		}
	}
	abufAppend(ab, "\x1b[m", 3);
	abufAppend(ab, "\r\n", 2);
}

void editorDrawMessageBar(struct abuf* ab) {
	abufAppend(ab, "\x1b[K", 3);
	int msglen = strlen(E.statusmsg);
	if (msglen > E.screencols) msglen = E.screencols;
	if (msglen && time(NULL) - E.statusmsg_time < 5) {
		abufAppend(ab, E.statusmsg, msglen);
	}
}

void editorRefreshScreen() {
	editorScroll();
	
	struct abuf ab = ABUF_INIT;
	
	abufAppend(&ab, "\x1b[?25l", 6);
	abufAppend(&ab, "\x1b[H", 3);
	
	editorDrawRows(&ab);
	editorDrawStatusBar(&ab);
	editorDrawMessageBar(&ab);
	
	char buf[32];
	snprintf(buf, sizeof(buf), "\x1b[%d;%dH", (E.cy - E.rowoff) + 1, 
												(E.rx - E.coloff) + 1);
	abufAppend(&ab, buf, strlen(buf));
	
	abufAppend(&ab, "\x1b[?25h", 6);
	
	write(STDOUT_FILENO, ab.b, ab.len);
	abufFree(&ab);
}

void editorSetStatusMessage(const char* fmt, ...) {
	va_list ap;
	va_start(ap, fmt);
	vsnprintf(E.statusmsg, sizeof(E.statusmsg), fmt, ap);
	va_end(ap);
	E.statusmsg_time = time(NULL);
}

/*** input ***/

char* editorPrompt(char* prompt, void (* callback)(char *, int)) {
	size_t bufsize = 128;
	char* buf = malloc(bufsize);
	
	size_t buflen = 0;
	buf[0] = '\0';
	
	while (1) {
		editorSetStatusMessage(prompt, buf);
		editorRefreshScreen();
		
		int c = editorReadKey();
		if (c == DEL_KEY || c == CTRL_KEY('h') || c == BACKSPACE) {
			if (buflen != 0) buf[--buflen] = '\0';
		} else if (c == '\x1b') {
			editorSetStatusMessage("");
			if (callback) callback(buf, c);
			free(buf);
			return NULL;
		} else if (c == '\r') {
				if (buflen != 0) {
					editorSetStatusMessage("");
					if (callback) callback(buf, c);
					return buf;
				}
			} else if (!iscntrl(c) && c < 128) {
				if (buflen == bufsize - 1) {
					bufsize *= 2;
					buf = realloc(buf, bufsize);
				}
				buf[buflen++] = c;
				buf[buflen] = '\0';
			}
			if (callback) callback(buf, c);
		}
}

void editorMoveCursor(int key) {
	erow* row = (E.cy >= E.numrows) ? NULL : &E.row[E.cy];

	switch(key) {
		case ARROW_LEFT:
			if (E.cx != 0) {
				E.cx--;
			} else if (E.cy > 0) {
				E.cy--;
				E.cx = E.row[E.cy].size;
			}	
			break;
		case ARROW_RIGHT:
			if (row && E.cx < row->size) {
				E.cx++;
			} else if (row && E.cx == row->size) {
				E.cy++;
				E.cx = 0;
			}
			break;
		case ARROW_UP:
			if (E.cy != 0)
				E.cy--;
			break;
		case ARROW_DOWN:
			if (E.cy != E.numrows)
				E.cy++;
			break;		
	}
	
	row = (E.cy >= E.numrows) ? NULL : &E.row[E.cy];
	int rowLen = row ? row->size : 0;
	if (E.cx > rowLen) {
		E.cx = rowLen;
	}
}

void editorProcessKeypress() {
	static int quit_times = KILO_QUIT_TIMES;
	
	int c = editorReadKey();
	
	switch(c) {
		case '\r':
			editorInsertNewline();
			break;
		
		case CTRL_KEY('q'):
			if (E.dirty && quit_times > 0) {
				editorSetStatusMessage("WARNING! File has unsaved changes. "
					"Press Ctrl-Q %d more times to quit.", quit_times);
				quit_times--;
				return;
			}
			write(STDOUT_FILENO, "\x1b[2J", 4);
			write(STDOUT_FILENO, "\x1b[H", 3);
			exit(0);
			break;
		
		case CTRL_KEY('s'):
			editorSave();
			break;
		
		case HOME_KEY:
			E.cx = 0;
			break;
		
		case END_KEY:
			if (E.cy < E.numrows)
				E.cx = E.row[E.cy].size;
			break;
		
		case CTRL_KEY('f'):
			editorFind();
			break;
		
		case BACKSPACE:
		case CTRL_KEY('h'):
		case DEL_KEY:
			if (c == DEL_KEY) editorMoveCursor(ARROW_RIGHT);
			editorDelChar();
			break;
		
		case PAGE_UP:
		case PAGE_DOWN:
			{
				if (c == PAGE_UP) {
					E.cy = E.rowoff;
				} else if (c == PAGE_DOWN) {
					E.cy = E.rowoff + E.screenrows - 1;
					if (E.cy > E.numrows) E.cy = E.numrows;
				}
				
				int times = E.screenrows;
				while (times--) editorMoveCursor(c == PAGE_UP ? ARROW_UP : ARROW_DOWN);
			}
			break;
		case ARROW_UP:
		case ARROW_DOWN:
		case ARROW_RIGHT:
		case ARROW_LEFT:
			editorMoveCursor(c);
			break;
		
		case CTRL_KEY('l'):
		case '\x1b':
			break;
		
		default:
			editorInsertChar(c);
			break;
			
		quit_times = KILO_QUIT_TIMES;
	}
}

/*** init ***/

void initEditor() {
	E.cx = 0;
	E.cy = 0;
	E.rx = 0;
	E.numrows = 0;
	E.rowoff = 0;
	E.coloff = 0;
	E.row = NULL;
	E.filename = NULL;
	E.statusmsg[0] = '\0';
	E.statusmsg_time = 0;
	E.dirty = 0;
	E.syntax = NULL;
	
	if (getWindowSize(&E.screenrows, &E.screencols) == -1) die("getWindowSize");
	E.screenrows -= 2;
}

int main(int argc, char** argv) {
	enableRawMode();
	initEditor();
	if (argc >= 2)
		editorOpen(argv[1]);
	
	editorSetStatusMessage("HELP: Ctrl-S = save | Ctrl-Q = quit | Ctrl-F = find");
	
	while (1) {
		editorRefreshScreen();
		editorProcessKeypress();
	}
	
	return 0;
}
